2022 Fiscal Year Final Research Report
Re-classification using species composition of fungus gnat pollinators for Arisaema serratum s.l. that cannot be distinguished from each other based on morphology
| Project/Area Number |
20K22668
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0703:Biology at organismal to population levels and anthropology, and related fields
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| Research Institution | Okayama University |
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Principal Investigator |
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| Project Period (FY) |
2020-09-11 – 2023-03-31
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| Keywords | テンナンショウ属 / 植物分類学 / 送粉者シフト / 種分化 / 生殖的隔離 |
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| Outline of Final Research Achievements |
The genus Arisaema (Araceae) has rapidly diversified in the Japanese archipelago and each species selectively attracts different fungus gnat pollinators. This species-specificity is caused by floral odor rather than flower appearance. If so, several cryptic species attracting different pollinators may be included in a known species which has been delimited using morphology. Therefore, (1) a search for cryptic species based on fungus gnat pollinator assemblage, (2) morphological comparisons and (3) evaluation of genetic differentiation between the cryptic species were conducted for 680 plants in 50 populations of Arisaema serratum s.l., that is widely distributed across Okayama Prefecture, western Japan. As a result, A. serratum included two distinct types that selectively attracted different fungus gnats but were indistinguishable based on morphology. Genetic differentiation was detected but was continuous between them. Thus, they seemed to be at a very early stage of speciation.
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| Free Research Field |
送粉生態学
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| Academic Significance and Societal Importance of the Research Achievements |
花の形態すなわち外見は，これまで重要な識別形質の一つとして，多くの植物分類群で用いられてきた．実際に，植物は多様な花のかたちを進化させることで，それぞれ異なる送粉者に適応してきた．送粉者の違いは系統間での遺伝的交流を抑制するため，種分化を駆動する重要な要因だとみなすことができる．しかし，送粉者の誘引手段は視覚だけではない．とりわけ嗅覚を利用して送粉者を誘引する場合，必ずしも種分化の過程で花形態の種間差が生じるとは限らず，形態に基づくこれまでの分類方法では種多様性の過小評価を招く危険性がある．本研究は，現にこの問題が存在することを示した数少ない事例であり，分類の方法論に新たな視点をもたらした．
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